Something on BoingBoing caught my attention:
"Vimeo user Flight404 uploaded a triptastic collection of hyperdelic music visualizations."
This started me thinking about two games.
AudioSurf proved that that outside music can create compelling ways to affect gameplay and user experience. As opposed to something like Rez where music was important, but was a side affect of a pre-determined level environment and user interaction.
Warning Forever blew me away with the way it made an evolving boss the core component of play.
Now what if someone combined these things into a bullet-hell shmup composed of a series of procedurally produced bosses and attack cycles as determined by whatever music you put into the game? Note, the graphics wouldn't have to be mind blowing, they just have to relate to the beat and intensity of the music being analyzed.
Its just a thought I had, if someone wants to run with it go ahead. My programming skills end somewhere between "Hello" and "World" so I won't be attempting this. I can only imagine the nightmare it would be, not only to program this, but to do so in a way that would make a fun game. Otherwise, I think its feasible.